PROJECT 1 Abstract Cardiovascular disease (CVD) risk is associated with poor food environments, which are characterized by limited access to affordable healthy foods. Such environments are extremely common in American Indian communities, yet, few studies have addressed food environments or food policies in Native communities. Retail food interventions that can expand access to healthy foods and stimulate community demand for healthier choices have shown promise in addressing CVD risk among American Indians. Citizens of the Chickasaw Nation, an Oklahoma tribe that is the 13th largest in the US, experience a disproportionate burden of CVD risk, along with substantial barriers to healthy eating. In 2014, 80% of almost 20,000 adult patients in the Chickasaw tribal health system had pre-hypertension or hypertension, while 84% were overweight or obese and 13% had diabetes. In collaboration with the Chickasaw Nation, we designed the Chickasaw Healthy Eating Environments in Retail Stores (CHEERS) study. This multilevel intervention will be conducted over 24 months in partnership with the first full-service, Chickasaw-owned supermarket, which will open in 2017. CHEERS comprises several mutually reinforcing strategies to improve blood pressure control in people with hypertension. We will implement CHEERS in the Chickasaw town of Ada, Oklahoma, while designating 2 other Chickasaw towns ? Sulphur and Tishomingo, Oklahoma ? as the control sites, since both lack a tribally-run supermarket. We will recruit 700 adults (350 per arm) with diagnosed hypertension and collect survey and clinical data at baseline, 12 months, and 24 months to assess the effects of CHEERS on blood pressure control and secondary outcomes (food purchasing, diet, and body mass index). Tribal members with uncontrolled hypertension will receive cookbooks featuring heart-healthy recipes tailored to traditional Chickasaw diets and culture, along with invitations to attend the healthy cooking demonstrations. During the intervention, a tribal media team will collect material to create a documentary film on its implications for public health and the local economy. The documentary will be disseminated to tribal leaders, who we will subsequently survey and interview to assess their readiness to implement CHEERS more widely. CHEERS will culminate in a multimedia presentation detailing the supermarket-based intervention and featuring personal success stories by hypertensive community members. Our Specific Aims are: 1) at the environmental level, to collect data on the availability, price, and shelf space devoted to healthy and less healthy options in existing local retail outlets at baseline (before the intervention) and again at 12 and 24 months; 2) at the individual level, to measure change in blood pressure and secondary outcomes among hypertensive community members at baseline and again at 12 and 24 months; and 3) at the policy level, to evaluate the documentary?s effect on tribal leaders? readiness to implement CHEERS across the Chickasaw Nation and other tribal communities. This study builds on preliminary data, best practices, established partnerships, and existing tribal resources to maximize the likelihood of success. Study findings and multimedia materials will provide much- needed evidence for tribally-run food interventions and will assist tribal nations in reducing CVD-related disparities by improving healthy food access.